These are hand-drawn overlays for use with VASL.  These are "special"
overlays, which do not exist in cardboard form.  They come in 1-5 hex
sizes and are numbered like the standard non-desert overlays (OG, O,
W, etc.)  Place the following files in a subdirectory named "overlays"
in the boards directory:

ovrSH (shellholes)
ovrV (vineyards)
ovrSR (stone rubble)
ovrWR (wooden rubble)
ovrWT (water)
ovrBR (bridge)

	The bridge overlays come in sizes of 1-7 hexes, such that hex
'1' is the first hex of the bridge and hex '2' is an adjacent land hex
connected by a road hexside.
